1. Field of the Invention
The present invention relates to an endoscope in which a distal end opening of a treatment instrument insertion channel provided in an insertion portion to be inserted into a subject is formed at a side surface of the insertion portion, and a treatment instrument elevator base is provided at a position facing the distal end opening of the treatment instrument insertion channel.
2. Description of the Related Art
In recent years, an endoscope having an observation optical system on a side of a distal end portion at a distal end side of an insertion portion of the endoscope in an insertion direction (hereinafter, simply referred to as the distal end side), what is called a side-view type endoscope, has been used to treat a disorder region in a digestive tract system, a pancreaticobiliary duct system, and the like.
Examples of treatments of pancreaticobiliary duct systems or the like using the side-view type endoscope include a diagnostic treatment for endoscopically imaging a bile duct or a pancreatic duct using an endoscope as well as a therapeutic treatment for collecting a bile stone existing in a choledoch duct or the like by a balloon or a gripping treatment instrument.
Furthermore, in the endoscope treatment for a pancreatic duct, a bile duct, a hepatic duct, or the like, since the pancreatic, the bile, and the hepatic ducts are extremely thin, it is challenging to insert a distal end portion of an insertion portion of an endoscope directly into such a duct.
Thus, in general, a distal end portion of an insertion portion of a side-view type endoscope is inserted to the vicinity of the duodenal papilla, and from there, under X-ray fluoroscopy, a guide wire protruding from a distal end opening of a treatment instrument insertion channel in an insertion portion is inserted into the foregoing ducts, the channel being formed in a side surface of the distal end portion of the insertion portion, and a treatment instrument such as a catheter is then selectively inserted into the pancreatic duct, the bile duct, or the hepatic duct with the guide wire as a guide.
According to the technique, once a guide wire is inserted into a pancreatic duct, a bile duct, or a hepatic duct, which is thin, treatment instruments can be inserted into and withdrawn from the duct through the guide wire repeatedly.
A guide wire or a treatment instrument is inserted into the duct through a distal end opening, in a treatment instrument insertion channel, by raising a known treatment instrument elevator base provided at a position facing the distal end opening.
Japanese Patent Application Laid-Open Publication Nos. 2002-34905 and 2003-305002 propose a technique with which when a treatment instrument is withdrawn from a pancreatic duct, a bile duct, or a hepatic duct, after the treatment instrument is withdrawn by raising a treatment instrument elevator base, from the foregoing ducts to a proximal end side in an insertion direction of an insertion portion (hereinafter, simply referred to as the proximal end side) with respect to a position at which the guide wire is bent, the treatment instrument elevator base is further raised, and thereby the guide wire is further raised to be retained between the treatment instrument elevator base and an insulating member at a proximal end side of a distal end opening to fix a position of the guide wire.
Specifically, Japanese Patent Application Laid-Open Publication No. 2002-34905 discloses a configuration in which on a guide plane that leads a guide wire or a treatment instrument on a treatment instrument elevator base, a substantially V-shaped or U-shaped groove in section is formed at a substantially center part of a planar view of the guide plane, and in a state where the guide wire is engaged in the groove, namely, a state where the guide wire is engaged in a center part of the guide plane, a treatment instrument elevator base is raised, and thereby the guide wire is retained and fixed between an insulating member and the groove in the treatment instrument elevator base in a shearing manner (hereinafter, referred to as the center lock configuration, and fixation of a guide wire at a center part of a guide plane is referred to as the center lock).
Furthermore, Japanese Patent Application Laid-Open Publication No. 2003-305002 discloses a configuration in which in a distal end opening, a treatment instrument elevator base is raised with a guide wire tilted toward a side of an observation optical system side provided with the distal end opening on a side surface of the distal end portion of the insertion portion, and thereby between an edge at a side close to the observation optical system of the treatment instrument elevator base and a run off portion of the close-side edge formed in an insulating member, the guide wire is more firmly retained and fixed than the center lock configuration by an edge surface and a surface of the run off portion (hereinafter, referred to as the side lock configuration, and fixation of a guide wire with the guide wire tilted toward the observation optical system side of the distal end opening is referred to as the side lock).
In general, since a guide wire is fixed within the scope of field of view of an observation optical system, the endoscope having the center lock configuration described in Japanese Patent Application Laid-Open Publication No. 2002-34905 or the side lock configuration described in Japanese Patent Application Laid-Open Publication No. 2003-305002 is sufficient.
However, although less frequently, an operator may experience a situation where in some cases, in a distal end opening, a guide wire has to be fixed with the guide wire tilted to a direction spaced apart from the observation optical system, the direction being out of the field of view of the observation optical system (for example, in a state where a guide wire cannot be led to a side lock configuration side, the guide wire must be fixed).
In view of such circumstances, similarly to the side lock configuration described in Japanese Patent Application Laid-Open Publication No. 2003-305002, by retaining a guide wire between a surface of an edge at a side spaced apart from an observation optical system of the treatment instrument elevator base and a surface of a run off portion of the spaced-side edge formed on an insulating member, the guide wire may be fixed with the guide wire tilted toward the side spaced apart from the observation optical system.